To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
From the early stage of providing voice-oriented services, a mobile communication system has evolved into a high-speed, high-quality wireless packet data communication system to provide data and multimedia services. Various mobile communication standards, such as High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), and Long Term Evolution-Advanced (LTE-A) of the 3rd Generation Partnership Project (3GPP), High Rate Packet Data (HRPD) of the 3rd Generation Partnership Project-2 (3GPP2), and IEEE 802.16, have recently been developed to support high-speed and high-quality wireless packet data communication services. In particular, an LTE system, developed to efficiently support high-speed wireless packet data transmission, maximizes wireless system capability using various wireless access technologies. An LTE-A system is an advanced wireless system of an LTE system and has enhanced data transmission capability compared to the LTE system.
In general, a base station and a user equipment that correspond to the Release 8 or 9 of the 3GPP standard organization are employed for the LTE system, and a base station and a user equipment that correspond to the Release 10 of the 3GPP standard organization are employed for the LTE-A system.
The 3GPP standard organization has standardized the LTE-A system and discussions are now being held regarding the standard for a subsequent Release with improved performance based on the standardized LTE-A system.
The existing 3rd Generation (3G) and 4th Generation (4G) wireless packet data communication systems such as HSDPA, HSUPA, HRPD, and LTE/LTE-A employ an Adaptive Modulation and Coding (AMC) scheme, a channel-sensitive scheduling scheme, and the like to improve transmission efficiency. When the AMC scheme is employed, a transmitter can adjust the amount of transmission data depending on a given channel state. That is, when channel state is poor, a transmitter may adjust the reception error probability to a desired level by reducing the amount of transmission data, and when a channel state is good, the transmitter may efficiently transmit a large amount of information while adjusting the reception error probability to a desired level by increasing the amount of transmission data. With the use of the channel-sensitive scheduling-based resource management method, the transmitter selectively provides a service to a user having a good channel state among a plurality of users, thus increasing the system capacity compared to the method of assigning a channel to one user and providing a service to the user with the assigned channel. Such a capacity increase as in the above description is referred to as “multi-user diversity gain.” In short, the AMC scheme and the channel-sensitive scheduling scheme are methods that allow a transmitter to apply an appropriate modulation and coding technique at a point of time that is determined to be most efficient based on partial channel state information fed back from a receiver.
The AMC scheme, when used together with a Multiple Input Multiple Output (MIMO) transmission scheme, may include a function of determining the rank or the number of spatial layers of a transmission signal. In determining the optimum data rate, the AMC scheme considers how many layers are to be used for transmission through the MIMO scheme, as well as a coding rate and a modulation scheme.
The MIMO scheme in which a wireless signal is transmitted using a plurality of transmission antennas may be classified into single user-MIMO (SU-MIMO) for transmission to one UE and multiuser-MIMO (MU-MIMO) for transmission to a plurality of UEs using the same time-frequency resource. In the SU-MIMO scheme, multiple transmission antennas transmit a wireless signal to one receiver through multiple spatial layers. At this time, the receiver has to include multiple reception antennas to receive the wireless signals through the multiple spatial layers. In contrast, in the MU-MIMO scheme, multiple transmission antennas transmit a wireless signal to multiple receivers through multiple spatial layers. The MU-MIMO has an advantage in that the receivers do not need multiple reception antennas, compared to the SU-MIMO. However, the MU-MIMO has a problem in that wireless signals are transmitted to the multiple receivers using the same frequency and time resource, thereby causing mutual interference between the wireless signals for the different receivers.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.